1. Field of the Invention
The present invention relates to a lens barrel for an AF single-lens reflex camera.
In an AF single-lens reflex camera, it has been in practice heretofore to effect a change between manual focusing (MF) and automatic focusing (AF) by an operation with a changeover switch provided at the side of the camera body. To describe this in detail, the conventional single-lens reflex camera is provided with an AF driving shaft which is rotated by a motor in the camera body while an interchangeable lens is provided with an AF driven shaft, which is driven by this AF driving shaft. The AF mode is defined by the state in which these two AF shafts, namely the AF driving shaft and the AF driven shaft, are interconnected. In this AF mode, the rotation of the AF driving shaft drives the AF driven shaft for its rotation. The focusing lens group is moved in the directional of the optical axis in accordance with the rotating motion of this AF driven shaft, and a focusing operation is thereby performed. Further, the focusing ring at the side of the lens is rotated at the same time as this movement.
The setting of the changeover from this AF mode to the MF mode is executed by cutting off the connection between the AF driving shaft positioned on the body side and the AF driven shaft provided on the lens. In this MF mode, the focusing ring on the lens, is rotated by the photographer's manual operation. Along with the rotation of this focusing ring, the focusing lens group is moved in the direction of the optical axis and performs a focusing operation.
This conventional lens barrel has its focusing ring moved in rotation even at a time when the AF mode is set. For this reason, consideration is given in such a way that the focusing ring will not interfere with the photographer's operation in the course of the AF operation, with such contrivances as making the focusing ring itself in a small size (that is, making the focusing ring in a narrow width) and arranging the focusing ring at the distal end part of the lens barrel. However, it has been pointed out as a problem, that a focusing ring made in a small size and arranged at the top end part of the lens barrel will on the contrary make it more difficult for the photographer to perform a manual operation on the focusing ring at the time when the camera is set in the MF mode. Also, as described above, the changeover switch for switching between the AF mode and the MF mode is provided on the side of the camera body, and it has therefore been pointed out as a problem, that it is hard to operate this changeover switch.